The present invention relates to stabilizers for light sensitive water soluble diazonium compounds and to presensitized reproduction materials such as lithographic plates having improved stability against the action of heat and/or moisture.
Presensitized reproduction materials such as used for planographic printing processes generally comprise a plate base or support member having a subbase coating or layer, over which is applied a photosensitive coating composition. The plate base may be a flexible sheet such as paper, plastic or metal which is treated to provide a hydrophilic or otherwise prepared surface upon which a photosensitive coating will adhere. In the case of metal plates, aluminum sheeting is most commonly employed as the base material having a grained or etched surface and/or a subbase formed by silica based coatings or by anodization of the aluminum in acidic electrolytic baths.
Diazonium compounds most commonly employed in the preparation of light sensitive compositions suitable for lithographic plate applications or photoresist applications may be characterized by the generic structure A--N.sub.2.sup.+ X.sup.-, wherein A is an aromatic or heterocylic residue and X is the anion of an acid.
Specific examples of light sensitive diazonium materials useful as aforementioned include higher molecular weight compositions obtained, for example, by the condensation of certain aromatic diazonium salts in an acid condensation medium with active carbonyl compounds such as formaldehyde, as disclosed for example in U.S. Pat. Nos. 2,063,631 and 2,667,415.
More recently, improved diazonium materials within the above generic formula have been developed which are faster, more adherable to support materials and exhibit lessened sensitivity to moisture. These include the reaction products having the composition of Formula I.
FORMULA I: At least one diazonium salt having the structure: ##STR1## wherein R.sub.1 is selected from the group consisting of --H, an alkoxy group having from 1 to 4 carbon atoms, and a 2-hydroxy-ethoxy group, and X.sup.- is the anion of the diazonium salt,
condensed with: PA0 wherein n is an integer from 1 to 4, R is a residue produced by the splitting off of n hydrogen atoms from a diphenyl ether, and R.sub.2 is an alkyl group with 1 to 4 carbon atoms, said condensation product containing, on the average, 0.25 to 0.75 unit derived from R(--CH.sub.2 --OR.sub.2).sub.n per diazo group. PA0 R'.sub.1 is an arylene group of the benzene or napthalene series PA0 R.sub.2 is a phenylene group PA0 R.sub.3 is a single bond or one of the groups PA0 R.sub.4 is selected from the group consisting of hydrogen, alkyl with 1 to 5 carbon atoms, aralkyl with 7 to 12 carbon atoms, and aryl with 6 to 12 carbon atoms, PA0 R.sub.5 is an arylene group having 6 to 12 carbon atoms PA0 Y is one of the groups --NH--, and --O-- PA0 X is an anion PA0 P is a number from 1 to 3 PA0 E is a residue obtained by splitting off m H atoms from a compound free of diazonium groups selected from the group consisting of aromatic amines, phenols, thiophenols, phenol ethers, aromatic thioethers, aromatic hetercyclic compounds, aromatic hydrocarbons and organic acid amines, PA0 R.sub.a is selected from the group consisting of hydrogen and phenyl, PA0 R.sub.b is selected from the group consisting of hydrogen and alkyl and acyl groups having 1 to 4 carbon atoms, and a phenyl group, and PA0 m is an integer from 1 to 10, PA0 R.sub.2 is a phenylene group PA0 R.sub.3 is a single bond or one of the groups PA0 R.sub.4 is selected from the group consisting of hydrogen, alkyl with 1 to 5 carbon atoms, aralkyl with 7 to 12 carbon atoms, and aryl with 6 to 12 carbon atoms, PA0 R.sub.5 is an arylene group having 6 to 12 carbon atoms --Y-- is one of the groups --NH--, and --O--, PA0 X is the anion of the diazonium compound, and PA0 p is a number from 1 to 3, and PA0 B is a radical of a compound selected from the group consisting of aromatic amines, phenols, thiophenols, phenol ethers, aromatic thioethers, aromatic hetercyclic compounds, aromatic hydrocarbons and organic acid amides, in which the aromatic nuclei are unsubstituted or substituted by at least one substituent activating condensation and selected from the group consisting of --NR.sub.7 R.sub.8, --N(R.sub.8).sub.2, --OR.sub.7, --OR.sub.8, --R.sub.8, and --SR.sub.8, PA0 R.sub.7 is --H, --CO-alkyl, --CO-aryl, --SO.sub.2 -alkyl, --SO.sub.2 -aryl, --COHN.sub.2, or --CSNH.sub.2, and PA0 R.sub.8 is -H, -alkyl, -aryl or -aralkyl, the alkyl groups having 1 to 10, the aryl groups 6 to 20 and the aralkyl groups 7 to 20 carbon atoms, PA0 m is 1 to about 9; PA0 Y is selected from the group consisting of --CH.sub.2 -- and --CH.sub.2 OCH.sub.2 --; and PA0 T is the same as R when Y is --CH.sub.2 -- and is hydrogen when Y is --CH.sub.2 --O--CH.sub.2 --, PA0 P.sub.1 may be the same as P or different; and PA0 X is an anion.
at least one compound of the general formula EQU R(--CH.sub.2 --OR.sub.2).sub.n PA1 q is a number from 0 to 5 PA1 r is a number from 2 to 5 PA1 q is a number from 0 to 5 PA1 r is a number from 2 to 5
Such materials are disclosed in U.S. Pat. No. 3,679,419, incorporated herein by reference.
Other diazonium compounds include the polycondensation products having the composition of Formula II.
FORMULA II: At least one A--N.sub.2.sup.+ X.sup.- compound condensed with at least one compound of the formula EQU E(CHR.sub.a --OR.sub.b).sub.m
in which A--N.sub.2 X is a radical of a compound selected from the group consisting of a compound of the formula EQU (R.sub.1 --R.sub.3).sub.p R.sub.2 --N.sub.2 X
and ##STR2## wherein R.sub.1 is an aryl group of the benzene or napthalene series
--(CH.sub.2).sub.q --NR.sub.4 -- PA2 --O--(CH.sub.2)--NR.sub.4 -- PA2 --S--(CH.sub.2).sub.r --NR.sub.4 -- PA2 --S--CH.sub.2 --CO--NR.sub.4 -- PA2 --O--R.sub.5 --O-- PA2 --O-- PA2 --S-- or --CO--NR.sub.4 -- PA2 --(CH.sub.2).sub.q --NR.sub.4 -- PA2 --O--(CH.sub.2).sub.r --NR.sub.4 -- PA2 --S--(CH.sub.2).sub.r --NR.sub.4 -- PA2 --S--(CH.sub.2).sub.r --CO--NR.sub.4 -- PA2 --O--R.sub.5 --O-- PA2 --O-- PA2 --S-- or PA2 --CO--NR.sub.4 --
the left-hand free valence of the specified groups is attached to R.sub.1 and the right-hand valence is attached to R.sub.2 wherein
are reacted in a strongly acid condensation medium and under condensation conditions sufficient to produce a polycondensation product of an aromatic diazonium compound containing, on the average, about 0.1 to 50 B.sub.1 units per unit of A--N.sub.2 X.
Still another diazonium materials include those materials having repeating units of the composition of Formula III.
FORMULA III: At least one A--N.sub.2.sup.+ X.sup.- compound condensed with at least one compound of the structure B, comprising repeating units of each of the general types A--N.sub.2 X and B which are linked by methylene groups, in which A--N.sub.2 X is a radical of a compound of one of the general formulae EQU (R.sub.1 --R.sub.3 --).sub.p R.sub.2 --N.sub.2 X
and ##STR3## wherein R.sub.1 is an arylene group of the benzene or naphthalene series
the left-hand free valence of the specified groups is attached to R.sub.1 and the right-hand free valence is attached to R.sub.2 wherein
wherein
which diazonium compound contains, on the average, about 0.01 to 50 B units per unit of A--N.sub.2 X.
Yet another category of extremely fast light sensitive diazos are those disclosed in copending application Ser. No. 359,335, filed in the U.S. Patent Office on Mar. 18, 1982, which is a continuation-in-part of Ser. No. 06/245,837, filed in the U.S. Patent Office on Mar. 20, 1981 now U.S. Pat. No. 4,436,804, issued Mar. 13, 1984. These materials may be characterized by the composition of Formula IV.
FORMULA IV: The condensation product of oligomers having the structure: ##STR4## wherein: R is selected from the group consisting of ##STR5## --CH.sub.2 OH, --CH.sub.2 O(CH.sub.2).sub.n CH.sub.3, ##STR6## --CH.sub.2 Cl, and --CH.sub.2 Br; n is an integer from 0 to 3; M is an aromatic radical of one or more compounds selected from the group consisting of aromatic hydrocarbons, diaryl ethers, diaryl sulfides, diaryl amines, diaryl sulfones, diaryl ketones and diaryl diketones;
with diazonium salts having the structure: ##STR7## wherein: R' is selected from the group consisting of phenyl, and C, to C.sub.4 alkyl substituted phenyl K is selected from the group consisting of ##STR8## --S--, --O--, and --CH.sub.2 --, or is absent; P and P.sub.1 are selected from the group consisting of C.sub.1 to C.sub.4 alkyl, methoxy, ethoxy, butoxy, and H;
Whereas recently developed, faster diazos offer many advantages in terms of speed and quality which render them extremely suitable in applications requiring low energy light exposure, including laser exposure applications, a major drawback is their decreased stability to heat. Whereas many of the less sensitive low molecular weight diazos exhibit a shelf life of weeks or months, under normal storage conditions, sensitized printing plates coated with the newer materials have a shelf life measured in hours, especially at higher storage temperatures.
Examples of prior art materials which are known diazo stabilizers in planographic printing plate applications include aryl and haloaryl sulfonic acids as taught in U.S. Pat. No. 2,649,373; phosphoric and sulfonic acids as taught in U.S. Pat. No. 3,679,419; benzophenone compounds as disclosed in U.S. Pat. No. 3,503,330; and diazo-borofluoride salts as taught in U.S. Pat. No. 3,933,499. U.S. Pat. No. 4,172,729 discloses a presensitized diazo lithographic plate having improved shelf life and printing performance containing up to 5% by weight of oxalic acid or a salt thereof as a stabilizer. The patent also comparatively recites the utilization of other additives such as citric, phosphoric, sulfonic, boric, sulfuric, polyphosphoric, adipic, sulfamic and tartaric acids as well as glycine and other acid salts.
Stabilizers have also been employed in two component light sensitive diazotype photographic compositions. These compositions are used in photographic processes where dyes are formed in-situ as the result of a coupling reaction between an undecomposed diazonium salt and a coupling component. The object of stabilization in these systems is to inhibit premature coupling of the diazonium salt and coupler during storage and prior to use. While the chemistry in such systems differs from the planographic systems disclosed herein, stabilizers similar to those employed in planographic systems have been suggested by the prior art.
Examples of such prior art stabilizers include aryl and haloaryl sulfonic acids and their salts as taught in U.S. Pat. No. 3,102,812; certain unsaturated organic acids such as crotonic, pentenic, sulfo cinnamic and derivatives of acrylic acid as taught in U.S. Pat. No. 2,354,088; certain anthranilic acids as taught in U.S. Pat. No. 2,496,240; certain acids such as tartaric, citric, boric, phosphoric and polyphosphoric such as taught in U.S. Pat. No. 3,615,574; certain acids including maleic, malonic, trichloroacetic, glyoxilic and sulfanilic as disclosed in U.S. Pat. No. 3,660,581; boric acid ester as disclosed in U.S. Pat. No. 3,679,421; certain organic acid amides, ketoacids, cyanoacids, cyclic acid derivatives, nitro acids and acetylenic acids as disclosed in U.S. Pat. No. 3,453,112; aromatic amines as disclosed U.S. Pat. No. 3,704,129; and saturated and unsaturated gamma lactones as disclosed in U.S. Pat. No. 2,374,563.
Whereas many of the aforementioned acid stabilizers might be considered suitable for the stabilization of any diazonium composition, it has been found that many of these acids affect the light sensitivity and speed of the diazonium composition. This is of particular disadvantage in the case of diazonium compound condensation products having the Formulas I through IV above since the enhancement of stability of such materials at the expense of speed and light sensitivity would render them of decreased utility in those applications where speed is of critical importance.
Accordingly, it is an object of this invention to provide light sensitive diazonium compound condensation product compositions having enhanced stability against heat and/or moisture and improved shelf life.
Another object is to provide light sensitive diazonium compound condensation product based photoresist materials and printing plates having enhanced stability and shelf life.
Another object is to impart increased shelf life to fast acting diazonium compound condensation product sensitized printing plates without a significant sacrifice of the speed of the diazo.